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Configuration

Configuration​

Exposing configuration is of fundamental importance to ensure the versatility of your application, but ensuring that said configuration comes in an expected format is also very important, you wouldn't want your app to still run and behave incorrectly would you?

npm i @basica/config

Basica validates configuration using Typebox.

service.ts
import { setTimeout } from "node:timers/promises"

export type Config = {
    delay: number
}

export class Service {

    constructor(private readonly config: Config) {}

    async delay() {
        console.log(`Waiting ${config.delay}ms`)
        await setTimeout(config.delay)
        console.log("Ok!")
    }
}
config.ts
import { Type } from "@sinclair/typebox";

export const schema = Type.Object({
  service: {
    delay: Type.Number({ minimum: 500, maximum: 5000, default: 1000 }),
  },
});

Environment variables​

Using the envProvider, we can read configuration from environment variables or a .env file into our app. By default, nested properties are concatenated with an underscore and variables are uppercase.

.env
SERVICE_DELAY=3000
note

Typebox records and arrays are parsed as json content.

const schema = Type.Object({
  // Variable WORKING_VALUE will work
  working: Type.Object({
    value: Type.String(),
  }),

  // Variable ONE_PROP won't work, use ONE='{ prop: "..." }' instead
  one: Type.Record(Type.String(), Type.String()),

  // Variable TWO_0 won't work, use TWO='["..."]' instead
  two: Type.Array(Type.String()),
});

const config = configure(configSchema, envProvider());
note

Typebox unions and intersections are also supported.

const schema = Type.Object({
  test: Type.Intersect([
    Type.Union([
      Type.Object({
        // Variable TEST_A
        a: Type.String(),
        // Either VARIABLE_D or VARIABLE_D_VALUE (VARIABLE_D takes precedence)
        d: Type.Union([Type.String(), Type.Object({ value: Type.String() })])
      }),
      Type.Object({
        // Variable TEST_B
        b: Type.String()
      })
    ]),
    Type.Object({
      // Variable TEST_C
      c: Type.String()
    })
  ]),
});

const config = configure(configSchema, envProvider());
index.ts
import { configure, envProvider } from "@basica/config"

import { Service } from "./service"
import { schema as configSchema } from "./config"

const config = configure(configSchema, envProvider())

const service = new Service(config.service)

await service.delay()
Waiting 3000ms
Ok!

API Docs​

Find the api docs on jsdocs.io